tersian

I've just been informed that I can get a rebuilt 454(stock out of a motorhome) for a steal. It was rebuilt by a local engine shop where I was looking at having my stroker rebuilt, but didn't have the cash at the time. The guy who has it is just looking to get out of it and he was real good friends with the owner of the shop and was charged very little to have it redone.

My question is, will a 454 fit, will I need to fabricate motor mounts and other parts? Will I have problems with brake booster locations, water pumps etc? What am I getting myself into potentially? Should I just stick to small blocks?

Thanks in advance guys.

Fevre

Will fit with the same SB motor mounts and will bolt to the same trans' as a SB but need new/different acc brackets, water pump, pullies, headers/manifolds. etc; believe the PB booster is fine with standard valve covers. Prolly add $1,000 +/- for all the extras.

markdtn

Short answer, yes it will fit.

You will need Vette specific pulleys, brackets, exh manifolds/headers. Will have to upgrade your radiator probably. Stock hood won't work unless you have a very flat intake. Do a search on this, there should be much info lurking in the archives.

tersian

Believe it or not, I did a search on 454 in the C3 section and I can't find much on the later C3's switching to a big block. I guess I really need to find out what this guy wants for the motor, it's a long block with the original heads and done .20 over. He didn't know what kind of pistons are in it but I can get all the specifics from the builder. I also need to find out what cam is in it. I did find out that the reason it needed rebuilt was that there were crank problems.

I was planning on spending 4-5k for a crate motor and all the accessories to make it work, assuming I can get this big block and all the pulleys and brackets for half of that, would it be worth it? What is a rebuilt 454 worth anyway(lets say it was rebuilt to a little better than stock)?

I guess I'm really wondering if it is worth it to go into this deal or just save my money for the small block.

Paul L

It will fit.

Jughead

I don't think there's anyone who regrets doing the 454 swap.

OK....someone will prove me wrong

Intimidator has a 454 on his PC

Corvus

If you decide not to put the BB, I'll buy yea a decent SB for it

And like somebody mentioned above, You will need a better radiator, as big block tend to overheat.

P.S. if it was .20 over it should be a 497.691

tersian

Just did an advanced search and found a bunch of info! Found out that I have 9.5" of clearance under the 81 hood and that I cannot be more than 8.55" from base to top of cleaner. Maybe that would let me run a better intake than the Torker II?

I'm going to call the guy tonight and see how much he wants for the 454 and what parts are already on it.

markdtn

Your motorhome type 454 is not going to have tremendously good parts on it for a Vette, particularly heads. Find out the casting number on the heads, they are likely small port. All you may get that you can use is a rebuilt 4-bolt shortblock.

Jughead

Were the motorohome blocks "Tall" blocks?

Get the casting number, located at the drivers rear on the block too. That'll give you more info.

check the casting number Here

markdtn

Not the ones I've dealt with, but still not great flowing heads on them.

kens 80

If you put a "BIG" big block , torque wise, the rear probably won't hold up. But it will fit quite easily. An auto trans will let the rear "live" a little longer than std trans.

Ak. Mal

Remember that the 454 in question was built for a motorhome. Not exactly a sporting type vehicle. It will probably have a "RV" cam in it which means tons of torque at lower rpms but not much horsepower up higher.

tersian

I haven't been able to get ahold of the guy all day, but when I do I will get the casting numbers off the heads and block then we'll know for sure.

matchframe

I did some research on Big Blocks before I found mine from a 91 Chevy Tow Truck.

You do have to be carefull about it being a tallblock..... there were a lot of tall blocks used in motorhomes. The best way to tell is if the top waterpump bolt holes are less than 1/2 inch from the deck, then it is a standard block. If the same holes are more than 1 inch from the deck, then it is a tall block. When I bought the 454 from the tow truck, I asked everybody I could find that knew big block and found that this was the best way, next to casting numbers, to determine if it were a tall or standard block... mine was standard.

If the 454 is a gen V or gen VI, which comes from a 1990 or later vehicle, it will not run as hot as the Mark IV 454 due to larger water ports. Because of these larger water ports you will have to use aftermarket heads designed for the later big blocks.... Edelbrock and AFR will work with the later generation blocks. You will still need to get a larger radiator.

Also, the heads are what is called "peanut port heads" They are great for low end torque, but have hardly any top end power. My 454 had these heads, and I plan to get some Edelbrock RPM oval port, or AFR oval ports to replace mine.

I was able to use the brackets and serpentine pulleys that came with my engine. You might be able to use the ones that came with your engine and save a pocketful of money.

Hope this helps!

www.bigdogvettes.com

Garys 68

Most tall decks were 427s, so it's probably a regular short deck.
The problem with that 454 is it will probably have the small oval "peanut" port heads and a cam made for low end torque. You may be dissapointed with 454 that's under 300hp.
If it's got large oval ports or rectangular, a cam switch alone may be a good option.
Gary

INTIMIDATOR ZO6

I'm very pleased with my swap. It really wasn't that bad... parts are out there! As for the hood question there is always the aftermarket!

EDDIEJ82

"My Gramdma....What a tall block you have!!!"

"All the better to stroke it with...My dear!!!"

John 65

This web site will answer all of your conversion questions. Enjoy

http://diabolicalperformance.com/c3bigblock.html

tersian

Would something like this work to solve the accessory bracket issue?



http://www.gmpartsdepot.com/store/pr...roduct_ID=1320